Foaming apparatus



Jan. 12, 1954 G. A. SPENCER Re. 23,772

FoAMING APPARATUS 5 Sheets-Sheet l Original Filed Feb. 3, 1950 IN VENTOR. c@

.Spaun l TTF/VEKS Jan. 12, 1954 G. A. 'SPENCER Re. 23,772

FOAMINGI APPARATUS Filed Feb'. s, 1950 3 Sheets-Sheet 2 iginal INVENTOR.)L

y Re. 23,772

Jan. l2, 1954 G, A. SPENCER FOAMING APPARATUS 5 Sheets-Sheet 5 OriginalFiled Feb. 5, 1950 IN VEN TOR. (uofd. Spenr BY gi/@fm A rra/mwlReissue-rl Jan. 12, 1954 zam FOALIING APPARATUS George A. Spencer,Akron, Ohio, assigner to The Firestone Tire Rubber Company, Akron,

Ohio, a corporation of Ohio original No. 2,581,918, dans January s,1952, sc-

rial No. 142,275, February 3, 1950. Application for reissue January 6,1953, Serial No. 329,942

Hatter enclosed in heavy brackets I', 1 appears in the original patentbut forms no part of this reissue specification; matter printed initalics .indicates the additions made by reissue.

9 Claims.

lto improvements in An important ob'ject of the invention is to providean apparatus in which a viscous material such as compounded rubber latexmay be introduced to be vigorously beaten or mixed in the presence of ametered amount of air for the production of a foamed product of uniformtexture.

Another object of the invention is to provide foaming equipment of highoutput capacity as compared to existing equipmentfand which in effect isself-cleaning to the extent that undesirable deposits, which necessitatefrequent cleaning of existing equipment, are either eliminated orminimized in a manner so that the normal operation of the equipment isnot affected thereby.

Another object is to provide improved foaming equipment particularlyadapted for the metered introduction of the product to be foamed, theair with which it is to be foamed, and certain additives, the latterbeing introduced subsequent to the initial stages of foaming.

Still another object of the invention is to provide foaming equipment ofrugged construction, manufacturable at relatively low cost as comparedto existing equipment, and requiring minimum maintenance and cleaningduring continuous use.

Another object of the invention is to provide foaming equipment whichoffers the above-outlined advantages over existing equipment, and doess0 while presenting a substantially lower internal back pressure thanheretofore obtained by any known type of equipment of comparable outputcapacity and physical dimensions.

An important object of the invention resides in the provision of a highspeed foaming unit of improved design and offering a uniform axial flowpath to the passage of material therethrough while said material isbeing continuously mixed with air and other ingredients, to maintain auniform pressure-area relationship throughout the entire foaming cyclefor the purpose of obtaining an end product of uniform cell construe.-v

tion.

Another important object of the invention is to construct a high speedmixer, the mixing elements of which may easily be regrouped in a. mannerto vary the axial spacing thereof for the purpose of readily adaptingthe mixer for use with liquid ingredients of widely varying vis-` 2 Acosity, or alternately, to vary, through wide limits, the output rate ofthe mixer.

Still other objects and advantages will become apparent to personsskilled in the art upon examination of the drawings, the specication,and the appended claims.

In the drawings, in which like parts are identified by the samereference numera throughout the various views.

Fig. 1 is an elevational view, partially sectionalized along the axis ofthe apparatus shown, and illustrating a mixing apparatus incorporating apreferred embodiment of the present invention;

Fig. 2 is a sectional view taken along line 2-2 of Fig. l;

Fiig. 3 is a sectional view along line 3-3 of Fig. 4 .is a section takenalong line 4 4 of Fig. 1; and

Fig. 5 is a diametric section of the stator portion of the mixer,showing disposition of the fixed blades.

As best shown in Fig. l, the device may include a foundation or base I0,of suitable construction,

5 such as a. metal casting or stamping, journal assemblies Il and I2,supportedabove base It by suitable brackets il, I5 and I6, Il,respectively; a mixing unit generically designated 2li, a casting 2|serving as a closure member for unit 2li, and including a bracketportion 22 for the rigid support of the mixer unit 20, preferably in thehorizontal position shown. Journal supporting brackets Il, I! and i6, I1may be cast. en bloc with supporting base lli to constitute uprightintegral extensions thereof, or may be otherwise fixed to base I0, forexample by being welded or bonded thereto. Bracket 2 may be of stainlessmetal in the event the mixer is to be employed for the foaming of latexwhich is normally compounded with corrosive ingredients, and includes agenerally planate portion 23, suitably apertured as hereinafterdescribed, leading into a base portion 24 clamped to the face of arecessed portion of base Ill, by clamping bolts 25.

A shaft 30. rotatably supported in journal assemblies Il and i2, extendsthrough an aperture provided in closure member 2| and into the mix- Aingunit. A rotor assembly within mixer unit 20,

as shown in Fig.'1, is mounted on a reduced diameter portion il of shaft3l) in ilxed relation thereto. The stator portion of unit 20 includes acylindrical housing 3l radially flanged at 35 for mounting to an annularintegral centering rib l! on casting 2|, by means ofclamping bolts M andll. Housing Il provides support for a plurality of axially positionedstator elements 38. each of 3 which includes a base portion l1 andintegral blade portions $8, of reduced thickness, and circumferentiallydisposed at regular intervals as shown in Figs. 4`and 5. The bases I1ofv stator elements Jl are of an axial dimension to permit saidelements, Vwhen assembled as shown, to be the marginal areas thereof.Nozzles Il through Il are disposed diagonally in respect to plateportion 1|, eachnozzle being provided with -I an inlet bore 1I leadinginto a reduced bore 1I maintained inv unitary clamped assembly between iannular shoulder Il of housing and the planate surface of bracketportion 2l, by means of clamping pressure appliedby clamping bolts Iland Il. A locking key I9, also shown in Fig. 4.

is axially disposed in suitable grooves to locli the base members 31 ofthe stator elements Il to housing 34 to prevent relative rotationtherebetween. The unsupported end of housing Il is iny ternally threadedat 40 for the threaded reception of an outlet spout I2, preferably acasting. provided with circumferentially spaced integral lugs Il tofacilitate assembly and removal of the outlet spout.

The rotor assembly within mixer unit 20, above mentioned as beingmounted on reduced portion I2 of shaft It in ilxed relation thereto,includes a plurality of axially mounted rotor elements I8, similar tostator elements I6 to the extent that each rotor element li-is providedlwith an annular Vdisposed cylindrical extending through closure .plate1I to terminate yat a position radially outwardly of a centrallyaperture 'Il provided-forreception of shaft il and packing gland housing1l. The relative position of the apertures denning the terminus of bores15 isbest shown at 1I, Fig. 3. The disposition of the nozzle bores 'Ilis such as -to terminate in registry with the annular chamber definedintermediate the base portions of stator assemblies 38 andJ rotorassemblies Il, in whichvboth the stator blades and rotor blades aredisposed. to feed vthe material to be foamed directly against the firstcircumferential series of y' rotor blades, as shown at 1I, Fig. l.

For the purpose of preventing the v entering housing Il through nozzlesIl through Il. from working through casting 2l between aperture 'Ittherein and shaft II, a conventional base portion Il and integrallyextending circumferentially spaced blade portions I9 of substantially'reduced thickness as compared to the base portion. During assembly ofthe unit 2|), the rotory elements I8 are concentrically received on asleeve Il, provided at its outer end with a radially flanged portion BIdefining an annular shoulder against which the rotor element firstmounted abuts. Sleeve 50, with rotor elements mounted thereon, is thenmounted as shown over the outer end of shaft portion I2. The baseportions Il of rotor elements 46 are of a thickness to insure positiveclamping of said elements in unitary assembly when sleeve B is securelyclamped against annular shoulder l defined by' the reduced portion 32 ofshaft III. Sleeve Il) and rotor elements 4i are maintained in clampedassembly. as above described. by a contoured cap member I2, providedwith a head screw 56 for threaded engagement with a suitable boreprovided in the end of shaft portion l2.

As shown in the broken view, Fig. 1, sleeve Il is sealing gland isprovided. This gland comprises a non-metallic sealing ring l! andaretaining ring 'II flanged at 81 to permit clamped engager ment ofplural clamping bolts ll threadedly engaged in casting 2| and providedwith nuts Il.

Since it may be desirable to introduce additives to the material aftereither partial or complete foaming has been eected. housing I4 may beprovided with one or more hypodermic type linjection needles,` such asneedle I2 extending from the exterior to the interior of housing 3l. Aconvenient method of introducing such a needle is through the provisionof a rubber plug Il, confined under compression within a suitablehousing aperture. For'example it may be desirable to introduce a gellingagent at a given point along the axial length of housing Il at aposition such interiorly provided with a splined section Il for lregistry with a mating spline section Il, provided exteriorly of shaftportion 32 throughout and end portion thereof. to constrain sleeveagainst relative rotation in respect to shaft 3l. The base of capelement l2 vis ofa diameter for registry with 'the flanged portion Il ofsleeve il -to provide a smoothly contoured diverging exit channel SIIfor the foamed product as it leavesthe blade assembly portion of thedevice to enter a connecting collar 8|. An axially extending key l2,shown in Fig. 4, prevents relative rotation between the rotor bladeassembly and sleeve Bl.

As best shown in Fig.`2, a plurality of inlet nozzleaare preferablyprovided Afor the purpose of equalizing the rate of materialintroduction to the device. While four such nozzles Il, il, l1, .and Ilare shown in 90 .angularity. it is underf into a semi-circular closureplate portion 1I of reduced thickness, the central portion of closure.plate 'Il being of thicker section, as at 1I, than as shown, whereinthe gelling agent is introduced into the foam in a manner to bethoroughly mixed therewith during the passage of the foam during travelthereof through the remainder of the mixer and prior to exit through theannular channel Il.

The construction of channel assemblies II and I2 may bein anyconventional manner. Assemp bly I2 as shown may include an annularhousing. II, which may be integralwith upright brackets I i and I1. Asuitable ball bearing assembly .I

is disposed within housing II and constrained against axial disp1acementby a closure plate Il, clamped to housing Il by-plural stud bolts ll. Ina like manner, journal assembly II may include a housing sl, integralwith upright brackets .I4 and Il and adapted to receive a ball bearingassembly IDU which may be of the type adapted to receive axial thrust ofshaft Il. This type of conventional bearing requires that shaft ll beprovided with a radially extending rib Il! and with an end collar I Ilretainedby nut Ill which threadedly engages a reduced and threaded Yextension I II1 of shaft Il. Inner race III of ball bearing assembly III,is maintained clampedbetween annular rib I'l2 and collar Ill to rotatewith shaft 20, while the outer race of ball bearing assembly |00 ismaintained clamped between an annular shoulderl I2 oi'housing I and theinner walls III of a housing-like cap assembly III', clamped to housingIl by a plurality 'of-stud bolts 1. Suitable oil-retaining seals |2l,and

|2I, |22 are provided in Journal assemblies and closure )l in a mannernot shown. Power may heap'- plied to pulley III through pluralv-beltsJll which maybe driven directly from a shaft pulley or throughconventional reduction machanism is merely illustrative, since it may hedesired to-drive shaft 3l by direct coupling' to the shmi'tof a motorwhich maintains a proper ilxed speed, or in any other conventionalmanner.

The advantages of the above described mixing apparatus are numerous',but outstanding among =these advantages are the reduction oi.' overalldimensions as compared to existing equipment and freedom 'from thenecessity oi' frequent cleaning during use. Heretotore mixers adaptedfor the roaming of such material as. latex and.. working vvon theprinciple oi'` ilxed and rotary lianes. have .beenof the so-called radiaT type. wherein the material to be i'oamed is introducedat'ajpositionrsdislly inwardly .ofV theblades, t be centrli'ugallythrown 'outwardly prio'r to passage through the blade structure.

which is large in comparison to the volume of the eective annular mixingpath. It is therefore not IOible to maintain a uniform'A pressurevolumerelationship within the device, since the work material is subjected toa higher pressure while'actually passing through the eiective mixingpath than 'it is subjected to leither .prior-to or 'subsequent to`leaving thatJpath but prior to exit from the mixer. n is wen knownuint-.vanaf tioiilin the pressure-volume relationship within the mxerresults in a foam of poorer quality and texture than is obtainable whenuniformity of the pressure-volume relationshipjis tained. 'I'heelimination, in the present mixer, of an inactive central chamber notonly permits substantial reduction in the diameter of the device, buttotally eliminates the highly undesirable condition of maintaining aninactive central chamber which has been proved highly detrimental to theproduction of quality foam.

In actual practice, va device designed to run at 4 speeds between 1150and 1175 R. P. M. may include a mixerunit the housing of ywhich has anoutside diameter oi no more than 'I or 8 inches. In such a device the`effective annular mixing chamber, defined between the base ot the rotorand stator blade assemblies, may have a mean diameter of, for example, 8inches and a radial width o! l inch or less. While such a 'mixenvworking on axial flow. ,is of greatly-reduced diameter as compared totheradial type of mixers heretofore employed, the volume output is asgreat or greater due-to the absence oi constricting oriiices which havelimited the output of the types heretofore known. For example, a mixerof the dimensions indicated above and operating at the speeds mentionedhas .a normal output in excess oi 1.000 pounds of foamed'latex per hour.The method oi' introduc- In t'thistypeoi mixer there isl of ynecessityan internal'volume Y asma . 6 ing. For example, a proximately inches inoutside diameter, 6

inches in axial length, and requiring 'l1/' horsepower input for thefoaming oi' latex at 350 R.. P. M; operating speed, has a constantoutput .capacity of800 pounds of foamedrubber per hour. Applicantsmixer, operating at 1150 R. P.v M., maintains an internal pressure inthe range -olfv ilve to. ten pounds per square inch, whereas the 20 inch'W2 horsepower input mixer mentioned above operates in the range o! to30 pounds internal pressure. A high internal pressure will of coursepromote expansion of the material at the outlet spout, due to pressuredi!- ferential in respect to the atmosphere, resulting inlarger-bubblesand a resulting coarser foam. Since smooth texture o! theend product is desirable, decrease in` bubble size is the ultimate vgoaloi'iany such mixer. at least when employed for the foaming oi.' latex.

As best shown in Fig. 5, the disposition oi' the stator blade assemblesis such that the radial extending blades Il of each blade assembly arestaggered circumferentially in respect to the blades or thev immediatelyadjacent assembly to restrict ire'e' ilow oi' the material between theseveral series .of blades. Thus the material enteringthe mixing chamberat 13 must not 'only' lpass'vthroughthe rapidly rotating stator blades,

with va. small am'ountpassing between the ends thereof and the statorhousingfut must follow a tortuous path presented by thecircumierentially overlapping disposition oi the stator blades. It isapparent, therefore, that while the .work material is not subjected toundesirable variations in chamber volume as it passes through the.mixer, 4which has resulted in blow-by 'in Ithe prior art devicesmentioned, complete admixture oi the material with air introduced towhich the stator blades are afiixed. By

proper disposition of the blades therein, a stator assembly, the bladesoi.' which are disposed in a generallyV helical configuration, may beinserted and removed by a so-called threading operation inwhich thestator assembly is worked into the rotorA assembly by a rotary movement.I n this adaptation of lthe invention, the dimensional limitations oithe blades may be empirically determined, in' respect to the normaloperating speed oi' -the device, to eliminate what 'would amount to alow resistance substantially open path, allowing transfer oi' materialthrough the device without proper mixing. While the adaptation shownincludes a plurality of both rotor and stator blade assemblies with anequal number of ing material to be roamed directly into the an .anyknown-type oi' comparable horsepower ratevenly spaced blades on eachassembly along theaxis of thedevice, it may be found desirable,especially for the proper mixing of certain materials, to vary the bladesize and the circumferential-spacing on each or some of the assemblies,as well as the axialV spacing therebetween. Thus a mixing deviceincorporating all-of the principles taught-herein might be of a designwhereby known type of mixer ap- I i 7 i. the incoming material and theair metered therewith is'subjected1 to a modest mixing action during theiir'st stage of axial flow through'the desarro' vice, tobe subjectedto'progressively increasing agitation during continued axial nowtherethrough, or converseLv` a; complete reversal of this suggestedarrangement might, under other circumstances,bedesirable.

'It is ofv course understood that the improved mixer described has wideapplicability, and that its use for the foaming of'latex, as wellas theprecise mechanical details included tor purpose" 8 radially fof saidshaft, a series of spaced rotor plates secured to said shaft and havingfingers disposed .radially of said shaft and extending into y the spacesbetween pairs of said stator plates, at

yleast one charging opening communicating with the interior of saidhousing, a generally conical ot exempliiication are'not tobe construedas l im itations. y

Whatisclaimedis:

[1. An apparatus for continuous production of vroamed liquid-airmixtures, which comprises a l central shaft with a plurality of iournalsupports,

an auxiliary support, through and beyond which said shaft extends, ahousing secured to said auxiliary support, cantilever fashion, and in`surrounding reiation to the extension ot saldshai't and having an exitpassage axially uned with said shaft, a series o! spaced stator platesinteriorl'y oi' said housing having ngers arranged radially of saidshaft, a series. of spaced, rotor plates secured to said shaft andhaving lingers disposed radiallyoi' said shaft and extending into thespaces between pairs oi' said stator plates, said auxiliary supporthaving charging openings cominunicating with the interior oi' said hous-[2. In a device asin claim 1, a generally conical head on the termnus ofthe said extension oi said shaft, and the said exit e on said housinghaving a converging form, defining, with said head, an annular,converging passage, leading to a final, tubular t [3, In a device as inclaim 2, a sleeve surrounding said shaft and keyed thereto and to saidrotor plates, a flange on said sleeve holding said plates in assembledrelation, and said head being a separate member, secured to said shai't,and overwhereby l head .ony the terminus 0f the said extension of vsaidshaft. and the said exit passage on said r housing having a convergingform, defining, with said head, an annular converging passage leading toa final tubular passage 10. An'apparatus for continuous production ofifoamed liquid air mixtures which comprises a central shaft withfour-nal support extending ,cantilever'fashiom a housing ysecured insurrounding relation to the extension of said shaft and having an exitpassage axially aligned with said shaft, a series of spaced statorplates interviorly of said housing having fingers arranged radially ofsaid shaft, al series of spaced rotor plates secured to said shaft andhaving fingers disposed radially of said shaft and extending into thespaces between pairs of said stator plates, at

least one charging opening lcommunicating with the interior of saidhousing. a generally conical head on the terminus of the said extensionof said shaft, a sleeve surrounding -said shaft and keyed thereto and tosaid rotor plates, a flange on said sleeve holding said plates inassembled relation, and said head being a separate member secured tosaid shaft, and overlying said flange, l to holdvsaid sleeve in positionon said shaft.A l

11. An apparatus for continuous production of foamed liquid air mixtureswhich comprises a central shaft with journal support Vextending lyingsaid flange, whereby to hold said sleeve in position on said shaft] f[4. A device as in claim 3, said sleeve having a iiplixied connectionwith said shaft] [5. A device as in claim 4. said housing beingdemountable from said auxiliary support where-- by said head may beremoved ior disassembly of said plates] [6. A device as in claim 1, saidcharging openings being arranged generally tangentially to a circleconcentric with the axis of said shaft, and

communicating at their termini directly with the space occupied by saidlingers] ['l. A device as in claim 1,*said charging open- I ings beingarranged generally tangentially to a circle concentric with the axis o!said shaft, and communicating at their termini directLv with thespaceoccupiedbysaidiingersandarrangedamcentral shaft with journalsupport extending cantilever fashion, a housing secured in surroundingrelation to the extension of said shaft and having an exit passageaxially aligned with said shaft. a series of spaced stator platesintericrly of said housing having fingers arranged cantilever'fashion, ahousing secured in surrounding relation to the extension of said shaftand having an exit passage axially aligned with said shaft, a series ofspaced stator plates interiorly of ,said housing having fingers arrangairadially of said shaft, a series of spaced rotor plates secured tosaidshaft an'd having fingers disposed vradially of said s haft andextending intothe spaces between pairs of said stator plates, at leastone charging opening communicating with the interior of said housing, agenerally conical head on the terminus of the said extension vof saidshaft,. a sleeve surrounding said shaft and splined thereto and to said.rotorplates, a

flange on said sleeve holding said plates in assembled -relation, andsaid head being a separate member secured to said shaft, and overlyingsaid flange, whereby to hold said sleeve in position on saidshaft.` o

12. An apparatus for continuous production of foamed liquid-air mixtureswhich comprises a central shaft with -fournal support extendingcantilever fashion," a housing secured in surrounding relation to theextension of said shaft and having an exit passage axially aligned withsaid shaft, a series of spaced stator plates interiorly of said housinghaving fingers arranged radially of said shaft, a series of spaced rotorplates .securedto said shaft and having fingers disposed radially ofsaid shaft and extending into the spaces between pairs ofV said statorplates, at least one charging opening communicating with the interior ofsaid housing, a generally conical head on the terminus of the saidextension of said shaft, said charging opening being arranged generallytangentially to a circle concentric with the axis of said shaft andcommunicating with the space occupied by said fingers.

v 13. An apparatus for continuous production of foamed liquid-airmixtures whichr comprises a central shaft with fournal support extendingcantilever fashion, a housing secured in surrounding relation to theextension of said shaft and having an exit passage axially aligned "withsaid shaft, a series of spaced stator plates interiorly `of said housinghaving fingers arranged radially of said shaft, a series of spaced rotorplates secured to said shaft and having fingers disposed radially ofsaid shaft and extending into the spaces between pairs of said statorplates, at least one charging opening communicating with the interior ofsaid housing, a generally conical head on the terminus of the saidextension of said shaft, said charging opening being arranged generallytangentially to a circle concentric with the axis of said shaft, andcommunicating directly with the space occupied by said'fingers andarranged angularly to a plane perpendicular to the axis of said shaft.

rounding relation to the extension of said shaft and having an exitpassage axially aligned with said shaft, a series of spaced statorplates interiorly of said housing having fingers arranged radially ofsaid shaft, a series of spaced rotor plates secured to said shaft andhaving fingers disposed radially of said shaft and extending into thespaces between pairs of said stator plates, at least one chargingopening communicating with the interior of said housing, a generallyconical head on the terminus of the said `extension of said shaft, thefingers of said stator platesbeing staggered in succession so as topresent only partial overlap in the adjacent fingers of adiacent plates.

1.5. An apparatus for continuous production of foamed liquid-'airmixtures, which comprises a central shaft with a plurality of journalsupports, an auxiliary support, through and beyond which said shaftextends cantilever fashion, a housing secured in surrounding relation tothe extension of said shaft and having an exit passage axially alignedwith said shaft, `a series of spaced stator plates interiorly of saidhousing having fingers arranged radially of said shaft, a series ofspaced, rotor plates secured to said shaft and having fingers disposedradially of said shaft and extending into the spaces between pairs ofsaid stator plates, said auxiliary support having charging openingscommunicating with the interior of said housing; said charging openingsbeing arranged generally tangentially to a circle asma concentric withthe axis of said shaft, and communicating directly with the spaceoccupied by said fingers.

16. An apparatus for continuous production of foamed liquid-airmixtures, which comprises a central shaft with a plurality of journalsupports, an auxiliary support, through and beyond which said shaftextends cantilever fashion, a housing secured in surrounding relation tothe extension of said shaft and having an exit passage axially alignedwith said shaft, a series of spaced stator plates interiorlg of saidhousing having fingers foamed liquid-air mixtures, which comprises a'central shaft with a plurality of fournal supports,

' an auxiliary support, through and beyond which said shaft extendscantilever fashion, a housing secured in surrounding relation to theextension of said shaft and having an exit passage axially aligned withsaid shaft, a series of spaced stator plates interiorly of said housinghaving fingers arranged radially of said shaft, a series of spaced,

rotor plates secured to' said shaft and having fingers disposed radiallyof said shaft and extending into the spaces between pairs of said statorplates, said auxiliary support having charging openings communicatingwith the interior of said housing; the fingers of said stator platesbeing staggered in succession so as to present only partial overlap inthe adfacent fingers of adjacent plates.

GEORGE A. SPENCER.

References Cited in the le of this patent or the original .patent UNITEDSTATES PATENTS 1Number Name Date l 1,449,623 Pfouts Mar. 27, 19231,487,208 Cooke et al Mal. 18, 1924 2,169,338 Dim; Aug..15, 1939 vFOREIGN PATENTS Number Country Date 689,465 France x May 27, 1930

